Researchers at Vanderbilt University have developed so-called “nanosponges” which can be used as a delivery system for anticancer drugs to tumors. They claim the method is three to five times more effective at reducing tumor growth than direct injection of the drugs. The tiny nanosponges are filled with a drug load and expose a targeting peptide that binds to radiation-induced cell surface receptors on the tumor. When the sponges encounter tumor cells they stick to the surface and are triggered to release their cargo. Benefits of targeted drug delivery include more effective treatment at the same dose and fewer side-effects. Studies so far have been carried out in animals with paclitaxel as the sponge load. Their findings are published in the June 1 issue of the journal Cancer Research.
From a Vanderbilt press release:
“We call the material nanosponge, but it is really more like a three-dimensional network or scaffold,” says Harth. The backbone is a long length of polyester. It is mixed in solution with small molecules called cross-linkers that act like tiny grappling hooks to fasten different parts of the polymer together. The net effect is to form spherically shaped particles filled with cavities where drug molecules can be stored. The polyester is biodegradable, so it breaks down gradually in the body. As it does, it releases the drug it is carrying in a predictable fashion.
“Predictable release is one of the major advantages of this system compared to other nanoparticle delivery systems under development,” says Harth. When they reach their target, many other systems unload most of their drug in a rapid and uncontrollable fashion. This is called the burst effect and makes it difficult to determine effective dosage levels.